Goniatites Zone (middle Mississippian) ammonoids of the Antler Foreland Basin (Nevada, Utah) DIETER KORN & ALAN L. TITUS The ammonoid faunas from the Goniatites Zone (Late Viséan; Mississippian) of the Camp Canyon Member (Chainman Formation) are described for the first time. The assemblage shows close relationships to time equivalent occurrences in Alaska and the American Midcontinent, but differs markedly from occurrences in Europe, North Africa, and the South Urals. Seven successive ammonoid biozones are proposed for this interval in North America, in ascending or- der: (1) Calygirtyoceras confusionense Ammonoid Biozone, (2) Calygirtyoceras arcticum Ammonoid Biozone, (3) Girtyoceras primum Ammonoid Biozone, (4) Girtyoceras gordoni Ammonoid Biozone, (5) Goniatites deceptus Ammonoid Biozone, (6) Goniatites eganensis Ammonoid Biozone, and (7) Goniatites multiliratus Ammonoid Biozone. The following ammonoid species are revised or newly described: Bollandoceras occidentale sp. nov., Entogonites burbankensis sp. nov., Entogonites borealis (Gordon, 1957), Entogonites acus sp. nov., Calygirtyoceras confusionense sp. nov., Calygirtyoceras arcticum Gordon, 1957, Girtyoceras primum sp. nov., Girtyoceras gordoni sp. nov., Girtyoceras hamiltonense sp. nov., Dimorphoceras worki sp. nov., Dimorphoceras rileyi sp. nov., Metadimorphoceras mangeri sp. nov., Metadimorphoceras richardsi sp. nov., Kazakhoceras bylundi sp. nov., Goniatites americanus Gordon, 1971, Goniatites deceptus sp. nov., Goniatites eganensis sp. nov., Goniatites sowerbyi sp. nov., and Praedaraelites loeblichi (Miller & Furnish, 1940). • Key words: Ammonoidea, Carboniferous, Mississippian, Viséan, Nevada, Utah, palaeobiogeography, biostratigraphy, Chainman Formation. KORN,D.&TITUS, A.L. 2011. Goniatites Zone (middle Mississippian) ammonoids of the Antler Foreland Basin (Ne- vada, Utah). Bulletin of Geosciences 86(1), 107–196 (60 figures, 37 tables, appendix). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received November 8, 2010; accepted in revised form January 24, 2011; published online March 8, 2011; issued March 14, 2011. Dieter Korn, Museum für Naturkunde, Leibniz Institute at the Humboldt University Berlin, Invalidenstraße 43, 10115 Berlin, Germany; [email protected] • Alan L. Titus, Grand Staircase-Escalante National Monument, Kanab, Utah 84741; [email protected] Goniatites de Haan, 1825 has the distinction of being one al. 2006), the South Urals (Bogoslovskaya 1966, Ruzhen- of the first named Carboniferous ammonoid genera. Even cev 1966), Novaya Zemlya (Kusina 1987, Kusina & Yats- though many species formerly assigned to the genus are kov 1999), Xinjiang (Liang & Wang 1991), Alaska (Gor- now referred to other genera like Arnsbergites, Lusitanoce- don 1957), and the United States Midcontinent (e.g. Girty ras, Paraglyphioceras, and Dombarites (Korn 1988), it 1909, 1911; Gordon 1962, 1965; Drahovzal 1972; Drahov- still has a 6 Ma chronostratigraphic range (Korn & Kauf- zal & Quinn 1972; Saunders et al. 1977). The stratigraphic mann 2009) and a nearly global distribution. The genus occurrence of this distinctive taxon was even considered ranges through a large part of the late Viséan (Asbian and evolutionarily significant enough to warrant Ramsbottom early Brigantian equivalent) and has been reported from & Saunders (1985) to establish its range as a formal Early the European North Variscan basins such as the British Carboniferous genus zone. Isles (e.g. Bisat 1924, 1934, 1952; Moore 1936, 1946, Goniatites also occurs in strata of North America’s 1952, 1958; Hodson & Moore 1959), the Rhenish Mounta- Antler Foreland Basin (Webster et al. 1984, Huh 1968), ins (e.g. Brüning 1923; Schmidt 1925; Nicolaus 1963; which extends over 2,500 km from Canada to south-east- Korn 1988, 1990, 1997a), the Ardennes (e.g. de Koninck ern California (Fig. 1) and resulted from subsidence caused 1880, Delépine 1940), the South Portuguese Zone (Korn by the formation of the Antler Orogenic Highland in the 1997b, Korn & Horn 1997), the Moroccan Meseta (Delé- Late Devonian and Mississippian (Eisbacher 1983). Antler pine 1941, Korn & Ebbighausen 2008), South Variscan ba- Foreland Basin strata is Late Devonian to early Pennsylva- sins such as the Cantabrian Mountains (Kullmann 1961), nian in age and locally richly fossiliferous, with ammonoids the Anti-Atlas of Morocco (Korn et al. 2005, 2007; Klug et occurring through most of the Early Carboniferous part of DOI 10.3140/bull.geosci.1242 107 Bulletin of Geosciences Vol. 86, 1, 2011 Figure 1. Palaeogeographic map of the eastern United States for the late Missis- sippian (modified after an image by Ron Blakey; http://jan.ucc.nau.edu/~rcb7/). Abbreviations: PF – Proximal Foredeep; MF – Medial Foredeep; DF – Distal Foredeep; SDM – Sierra Diablo Moun- tains; LU – Llano Uplift; AM – Ar- buckle Mountains; OP – Ozark Plateau. Figure 2. Map of east-central Nevada showing ammonoid localities. Abbrevi- ations: DW – Duckwater Hills; CC – Cathedral Canyon; HC – Hamilton Can- yon; TSC – Trough Springs Canyon; RS – Rosebud Spring; PEC – Pony Ex- press Canyon. Dark grey shading shows Mississippian outcrops. the sequence (Gordon et al. 1957; Gordon 1970, 1986; ingly, the only previously published systematic treatments Webster et al. 1984; Petersen et al. 2000; Titus 2000; Work of Goniatites Zone (sensu Ramsbottom & Saunders 1985) et al. 2000; Titus & Manger 2001). Late Viséan (Asbian ammonoids from the Antler Foreland Basin are two brief and Brigantian of the British stratigraphic scheme) studies of three taxa (Miller et al. 1949, Gordon 1971). ammonoids are particularly common in the shale and car- In 1992, ALT began measuring sections and collecting bonate sequences of eastern Nevada and western Utah, and ammonoids from within the Antler Foreland Basin in east- to a lesser extent of southern Idaho (Huh 1968). Surpris- ern Nevada and western Utah (Figs 2, 3) for his dissertation 108 Dieter Korn & Alan L. Titus Goniatites Zone (middle Mississippian) ammonoids, Nevada and Utah Figure 3. Map of west-central Utah showing ammonoid localities. Abbrevia- tions: NR – Needle Range; SBH – South Burbank Hills; JW – Jensen Wash; CMW – Conger Mountain West; CME – Conger Mountain East; MC1–MC3 – Middle Confusion Range 1–3; BSH – Bishop Springs Dome; GM – Granite Mountain. Dark grey shading shows Mississippian outcrops. research. Only late early Serpukhovian (Arnsbergian Previous work Stage) material was treated systematically in this work (Ti- tus 2000), but a large number of early Serpukhovian Antler Foreland Basin (Pendleian) and late Viséan ammonoid specimens were also assembled. The new material led ALT to the conclu- Inexplicably, nearly all material in early collections from sion that the Antler Foreland Basin’s Late Viséan the study area is Serpukhovian in age (e.g. Hall & Whitfield ammonoid record was much more continuous, diverse and 1877; Miller & Furnish 1940; Youngquist 1949a, 1949b). significant than reported in its most recently published re- The region’s first description of ammonoids from the Go- view by Webster et al. (1984). niatites Zone was by Miller et al. (1949; plate 99, Over the course of the next 15 years, ALT continued to figs 7–10), who illustrated specimens of Goniatites and collect stratigraphically located Late Viséan ammonoid Girtyoceras collected from the White Pine Range area of material from Nevada and Utah, which forms the bulk of east-central Nevada. We could not relocate the locality, this study. Subsequent collections made by ALT with the and the specimens are immature, but we can still make con- assistance of Nicholas J. Riley, Barry Richards, and DK fident species level assignments: ‘Goniatites choctawensis have greatly refined the biostratigraphic resolution of the Shumard, 1863’ (= Goniatites eganensis sp. nov.), succession around the Asbian–Brigantian stage boundary ‘Girtyoceras aff. G. meslerianum (Girty, 1909)’ (= Girtyo- and confirmed the region contains a remarkable, previ- ceras hamiltonense sp. nov.). ously undocumented high-resolution record of the evolu- The first substantial collections of Asbian and early tion of Goniatites and other contemporaneous ammonoid Brigantian ammonoids from the region were made in the taxa. This systematic review of newly collected material late 1950s by mapping teams from the United States Geo- establishes a high-resolution Asbian–early Brigantian logical Survey working in west-central Utah. Although ammonoid biostratigraphic zonation for the Antler Fore- biostratigraphic analyses of these collections were made by land Basin and documents ammonoid diversity for that Mackenzie Gordon Jr. (Gordon et al. 1957, Gordon 1970, time. Our work has also shown that recent advances in the Webster et al. 1984), most of this material has only been re- phylogeny and biostratigraphy of Viséan ammonoids ported through faunal lists. The single systematic paper (Korn 1988, 1996), as well as our new data from the Ant- that resulted from these collections (Gordon 1971) named ler Foreland Basin region, has necessitated restudy of Goniatites americanus using specimens collected at Gran- even seemingly well-known North American assem- ite Mountain, Juab County, Utah as the primary types. blages. The most recent published work on these assemblages 109 Bulletin of Geosciences Vol. 86, 1, 2011 (Webster et al. 1984) lists, in ascending order, the follow- taxa from the Kuna Formation that we consider contempo- ing taxa (with our revisions): raneous with the assemblages in this study: ‘Bollandites